1988 Chevy S-10 6 cyl Four Wheel Drive Automatic 100, 00 miles
All forward gears fail, only reverse. Replaced trans. With new kit, pump, seals, solenoid, planetary gears torque converter. Re-installed it changes gears perfectly, then after a mile driving, loud noise, completely shears gear above planatary. Happened three times. Someone suggested problem in casing that caused the gears to work against each other. Appreciate your diagnosis. This is a 700 R4 automatic transmission.
This is something only a visual inspection by a qualified, trans person can do. It can be anything from a cracked case, leaking valve body, hardly anything. That's why you need to have a qualified person look at it. It could also have a missing thrust bearing that caused this.